1. Field of the Invention
This invention relates to a technique for reducing the fuel consumption of a vehicle by controlling an engine and transmission.
2. Description of the Related Art
JP2002-89349A, which was published in the year 2002 by the Japan Patent Office, discloses an evaluation system for vehicle operating conditions that provides objective evaluation standards for operating conditions by specifically showing the operating conditions including the fuel economy to the driver and the administrator. According to this system, the driver can improve his or her driving techniques by referring to the provided evaluation standards.
However, even were useful evaluation standards to be presented, an improvement in driving techniques cannot be expected, and fuel economy cannot be improved if the presented information is not appropriately used. In situations where the amount of fuel consumed must be reduced, the vehicle must be actively controlled by means of a controlling device so that fuel efficiency improves without relying solely on the driver""s voluntary improvement in driving techniques.
An object of this invention is therefore to improve fuel efficiency by controlling the engine and transmission without regard to the intention of the driver.
The vehicle provided by this invention comprises an engine, a transmission connected to the engine, a detecting device for detecting the current speed of the vehicle, a detecting device for detecting the current gear position of the transmission and a controller. The controller sets the difference between the maximum drive force of the vehicle at the current vehicle speed and gear position, and the running resistance at the current vehicle speed as the spare drive force; sets the difference between the current drive force of the vehicle and the running resistance at the current vehicle speed as the excess drive force; and controls the engine or the transmission of the vehicle so as to reduce the ratio of the excess drive force to the spare drive force.
According to this invention, an excess drive force greater than that which is necessary from the viewpoint of the drive force required for running can be prevented from being exerted, the amount of fuel consumed can be reduced, and the fuel efficiency of the vehicle can be improved because the engine and the transmission are controlled so as to reduce the ratio of excess drive force (=current drive forcexe2x88x92running resistance) to spare drive force (=maximum drive forcexe2x88x92running resistance).
The embodiments of this invention and the advantages of this invention are described in detail below with reference to the attached diagrams.